Pancratic objective

ABSTRACT

An objective of the pancratic type includes a varifocal front lens group and a fixed-focus rear lens group, the latter consisting of five air-spaced singlets. The front lens group is constituted by a positive first component consisting of three singlets, an axially shiftable negative second component consisting of a singlet and a doublet, and an axially shiftable positive third component in the form of a nearly planoconvex singlet of low power.

FIELD OF THE INVENTION

Our present invention relates to an optical objective of the pancraticor varifocal type comprising a front lens group of variable focal lengthand a fixed-focus rear lens group, the front group consisting of asubstantially stationary positively refracting first component (whichmay be limitedly shiftable for focusing purposes), an axially shiftablenegatively refracting second component and an axially shiftablepositively refracting third component.

BACKGROUND OF THE INVENTION

Objectives of the so-called XL (=existing light) class, designed to takeindoor pictures without additional illumination, generally have relativeapertures of about 1:1.3 or larger. In many instances, as described forexample in commonly owned U.S. Pat. No. 3,989,349, the rear lens groupof such an objective consists of five air-spaced lens members. In anobjective of the type here contemplated, e.g. as known from U.S. Pat.Nos. 3,044,355, 3,074,317 and 3,580,662 as well as German publishedspecification No. 2,526,847, the diaphragm is usually locatedimmediately in front of this rear lens group and is preceded by theshiftable positive third component. Obviously, this third component aswell as the lenses of the rear group must have diameters compatible withthe overall relative aperture as determined by the interposed diaphragm;thus, the third component must be a fairly large lens member thoughgenerally smaller than the member or members of the front componentwhose diameter determines the field of view.

Unless the third component is a lens member of large individual focallength f₃, its spherical aberrations create problems which heretoforewere resolved by designing this lens member as a cemented doublet. Anexcessive increase of focal length f₃ generally leads to objectionablylarge dimensions for the varifocal front group or necessitates areduction in the varifocal ratio if the desired large relative apertureis to be preserved. As a practical rule, the individual focal length f₂of the second (negative) component should be on the same order ofmagnitude as the median overall focal length f_(med) of the entireobjective, i.e. the focal length existing at the inversion point of thepath of the third component which then lies in a position farthest fromthe rear lens group. With modern objectives, the preferred absolutevalue of f₂ ranges between about 0.7 and 1.5 times f_(med).

OBJECT OF THE INVENTION

The object of our present invention is to provide a pancratic objectiveof the aforedescribed type which, with a varifocal ratio of almost 3:1and a relative aperture of at least 1:1.3, allows the use of a singlelens as the positive third component without unduly increasing the totalaxial length of the objective.

SUMMARY OF THE INVENTION

We have found, in accordance with our present invention, that thisobject can be realized by making the ratio between the absolute valuesof the individual focal lengths of the third and second components, i.e.f₃ /|f₂ |, greater than 1.5 times the varifocal ratio R_(v) =f_(max)/f_(min) where f_(max) is the maximum and f_(min) is the minimum overallfocal length.

Advantageously, f₂ has an absolute value less than f_(med), preferablyabout 4f_(med) /5.

BRIEF DESCRIPTION OF THE DRAWING

The above and other features of our invention will now be described indetail with reference to the accompanying drawing in which:

FIG. 1 shows a pancratic objective according to our invention in awide-angle position corresponding to an overall focal length f_(min) ;

FIG. 2 shows the same objective in an intermediate positioncorresponding to an overall focal length f_(med) ; and

FIG. 3 shows that objective in a telephoto position corresponding to anoverall focal length f_(max).

SPECIFIC DESCRIPTION

The objective shown in the drawing consists of a substantially fixedfirst component G₁ of positive refractivity, an axially shiftable secondcomponent G₂ of negative refractivity, an axially shiftable thirdcomponent G₃ of positive refractivity, and a rear group G₄ composed offive air-spaced lenses. A diaphragm B is interposed between componentsG₃ and G₄. The image plane of the objective has been shown at P.

Component G₁ consists of three air-spaced singlets, namely a front lensL₁ in the form of a negative meniscus with radii r₁, r₂ and a thicknessd₁, a positive lens L₂ with radii r₃, r₄ and a thickness d₂, and apositive lens L₃ with radii r₅, r₆ and a thickness d₃. Component G₂consists of a negative singlet L₄ (radii r₇, r₈ and thickness d₄) and adoublet composed of a negative lens L₅ (radii r₉, r₁₀ and thickness d₅)and a positive lens L₆ (radii r₁₀, r₁₁ and thickness d₆). Component G₃is a positive singlet L₇ (radii r₁₂, r₁₃ and thickness d₇). The fivesinglets making up the rear component G₄ are a generally planoconvexlens L₈ (radii r₁₄, r₁₅ and thickness d₈), a positive meniscus L₉ (radiir₁₆, r₁₇ and thickness d₉), a biconcave lens L₁₀ (radii r₁₈, r₁₉ andthickness d₁₀), a generally planoconvex lens L₁₁ (radii r₂₀, r₂₁ andthickness d₁₁), and a generally planoconvex lens L₁₂ (radii r₂₂, r₂₃ andthickness d₁₂). The air spaces separating the several lens members fromone another have been designated s₁ -S₁₀.

Advantageously, the more strongly curved side of lens L₈ is its frontsurface r₁₄ whose surface power Φ₁₄ ranges between 0.4 and 0.7 timesΦ_(med), the latter being the overall power of the objective in itsmedian position corresponding to focal length f_(med). The forwardlyfacing convex surface r₁₆ of lens L₉ should have a surface power Φ₁₆ranging between 0.6Φ_(med) and 0.9Φ_(med). The surface powers Φ₁₈ andΦ₁₉ of the front and rear surfaces r₁₈ and r₁₉ of lens L₁₀ arepreferably related to each other by a ratio of Φ₁₉ /Φ₁₈ ranging betweenunity and 2.5. The convex rear surface r₂₁ of lens L₁₁ should have apower Φ₂₁ ranging between 0.7 Φ_(med) and Φ_(med). The same applies tothe surface power Φ₂₂ of the convex front surface of lens L₁₂. These twolast lenses L₁₁ and L₁₂ may in fact be mirror images of each other.

In the following Tables I-VII we have given specific numerical valuesfor the radii r₁ -r₂₃, the lens thicknesses d₁ -d₁₂, the separations s₁-s₁₀, the refractive indices n_(d) and the Abbe numbers ν_(d) of lensesL₁ -L₁₂ for a number of representative embodiments. The radii,thicknesses and separations are based upon a numerical value of unityfor the median overall focal length f_(med). Air space s₆ consists of avariable distance, separating lens L₇ from diaphragm B, and aninvariable distance between that diaphragm and lens L₈.

                                      TABLE I                                     __________________________________________________________________________                 Thicknesses and      Surface                                     Lens Radii   Separations    n.sub.d                                                                          ν.sub.d                                                                       Powers                                      __________________________________________________________________________         r.sub.1 = +6.386                                                         L.sub.1      d.sub.1 =                                                                           0.106    1.805                                                                            25.4                                                r.sub.2 = +1.994                                                                      s.sub.1 =                                                                           0.143                                                           r.sub.3 = +2.704                                                         L.sub.2      d.sub.2 =                                                                           0.305    1.603                                                                            60.6                                                r.sub.4 = - 13.757                                                                    s.sub.2 =                                                                           0.006                                                           r.sub.5 = +1.724                                                         L.sub.3      d.sub.3 =                                                                           0.373    1.658                                                                            50.9                                                r.sub.6 = -42.460                                                                           0.050 f.sub.min                                                         s.sub.3 =                                                                           0.588 f.sub.med                                                               0.911 f.sub.max                                                 r.sub.7 = -72.759                                                        L.sub.4      d.sub.4 =                                                                           0.059    1.713                                                                            53.8                                                r.sub.8 = +0.821                                                                      s.sub.4 =                                                                           0.165                                                           r.sub.9 = -2.395                                                         L.sub.5      d.sub.5 =                                                                           0.056    1.589                                                                            61.3                                                r.sub.10 = +0.914                                                        L.sub.6      d.sub.6 =                                                                           0.149    1.805                                                                            25.4                                                r.sub.11 = +2.836                                                                           1.031 f.sub.min                                                         s.sub.5 =                                                                           0.725 f.sub.med                                                               0.179 f.sub.max                                                 r.sub.12 = +2.091                                                        L.sub.7      d.sub.7 =                                                                           0.137    1.517                                                                            64.2                                                r.sub.13 = -11.609                                                                          0.581+0.280 f.sub.min                                                   s.sub.6 =                                                                           0.348+0.280 f.sub.med                                                         0.572+0.280 f.sub.max                                           r.sub.14 = +1.027            Φ.sub.14 = +0.6037                      L.sub.8      d.sub.8 =                                                                           0.211    1.620                                                                            60.3                                                r.sub.15 = -10.449                                                                    s.sub.7 =                                                                           0.006                                                           r.sub.16 = +0.812            Φ.sub.16  = +0.7685                     L.sub.9      d.sub.9 =                                                                           0.137    1.624                                                                            47.0                                                r.sub.17 = +1.684                                                                     s.sub.8 =                                                                           0.137                                                           r.sub.18 = -1.534            Φ.sub.18  = -0.5522                     L.sub.10     d.sub.10 =                                                                          0.140    1.847                                                                            28.8                                                r.sub.19 = +0.773            Φ.sub.19 = -1.0957                                   s.sub.9 =                                                                           0.211                                                           r.sub.20 = -56.811                                                       L.sub.11     d.sub.11 =                                                                          0.165    1.713                                                                            53.8                                                r.sub.21 = -0.786            Φ.sub.21 = +0.9071                                   s.sub.10 =                                                                          0.006                                                           r.sub.22 = +0.855            Φ.sub.22  = +0.8386                     L.sub.12     d.sub.11 =                                                                          0.118    1.717                                                                            48.0                                                r.sub.23 = +2.356                                                        __________________________________________________________________________     f.sub.min = 0.591                                                             f.sub.med = 1                                                                 f.sub.max = 1.632                                                             relative aperture = 1:1.3                                                     f.sub.2 = -0.808                                                              f.sub.3 = +3.441                                                         

                                      TABLE II                                    __________________________________________________________________________                 Thicknesses and      Surface                                     Lens Radii   Separations    n.sub.d                                                                          ν.sub.d                                                                       Powers                                      __________________________________________________________________________         r.sub.1 = +6.397                                                         L.sub.1      d.sub.1 =                                                                           0.106    1.805                                                                            25.4                                                r.sub.2 = +1.968                                                                      s.sub.1 =                                                                           0.143                                                           r.sub.3 = +2.585                                                         L.sub.2      d.sub.2 =                                                                           0.304    1.603                                                                            60.6                                                r.sub.4 = -13.657                                                                     s.sub.2 =                                                                           0.006                                                           r.sub.5 = +1.700                                                         L.sub.3      d.sub.3 =                                                                           0.360    1.651                                                                            55.9                                                r.sub.6 = -70.269                                                                           0.046 f.sub.min                                                         s.sub.3 =                                                                           0.584 f.sub.med                                                               0.907 f.sub.max                                                 r.sub.7 = ∞                                                        L.sub. 4     d.sub.4 =                                                                           0.059    1.713                                                                            53.8                                                r.sub.8 = +0.836                                                                      s.sub.4 =                                                                           0.165                                                           r.sub.9 = -2.796                                                         L.sub.5      d.sub.5 =                                                                           0.056    1.643                                                                            58.0                                                r.sub.10 = +0.897                                                        L.sub.6      d.sub.6 =                                                                           0.149    1.847                                                                            23.8                                                r.sub.11 = +2.697                                                                           1.055 f.sub.min                                                         s.sub.5 =                                                                           0.748 f.sub.med                                                               0.194 f.sub.max                                                 r.sub.12 = +2.375                                                        L.sub.7      d.sub.7 =                                                                           0.137    1.691                                                                            54.7                                                r.sub.13 = ∞                                                                          0.578+0.155 f.sub.min                                                   s.sub.6 =                                                                           0.348+0.155 f.sub.med                                                         0.578+0.155 f.sub.max                                           r.sub.14 = +1.504            Φ.sub.14 = +0.4122                      L.sub.8      d.sub.8 =                                                                           0.186    1.620                                                                            60.3                                                r.sub.15 = -6.705                                                                     s.sub.7 =                                                                           0.006                                                           r.sub.16 = +0.864            Φ.sub.16 = +0.7176                      L.sub.9      d.sub.9 =                                                                           0.145    1.620                                                                            60.3                                                r.sub.17 = +2.120                                                                     s.sub.8 =                                                                           0.205                                                           r.sub.18 = -1.686            Φ.sub.18 = -0.5024                      L.sub.10     d.sub.10 =                                                                          0.140    1.847                                                                            23.8                                                r.sub.19 = +0.895            Φ.sub.19 = -0.9464                                   s.sub.9 =                                                                           0.261                                                           r.sub.20 = +9.224                                                        L.sub.11     d.sub.11 =                                                                          0.174    1.713                                                                            53.8                                                r.sub.21 = -0.963            Φ.sub.21 = +0.7404                                   s.sub.10 =                                                                          0.006                                                           r.sub.22 = +0.905            Φ.sub.22 = +0.7923                      L.sub.12     d.sub.12 =                                                                          0.124    1.717                                                                            48.0                                                r.sub.23 = +4.502                                                        __________________________________________________________________________     f.sub.min = 0.590                                                             f.sub.med = 1                                                                 f.sub.max = 1.637                                                             relative aperture = 1:1.2                                                     f.sub.2 = -0.307                                                              f.sub.3 = +3.437                                                         

                                      TABLE III                                   __________________________________________________________________________                 Thicknesses and      Surface                                     Lens Radii   Separations    n.sub.d                                                                          ν.sub.d                                                                       Powers                                      __________________________________________________________________________         r.sub.1 = +6.397                                                         L.sub.1      d.sub.1 =                                                                           0.106    1.805                                                                            25.4                                                r.sub.2 = +1.968                                                                      s.sub.1 =                                                                           0.143                                                           r.sub.3 = +2.585                                                         L.sub.2      d.sub.2 =                                                                           0.304    1.603                                                                            60.6                                                r.sub.4 = -13.656                                                                     s.sub.2 =                                                                           0.006                                                           r.sub.5 = +1.700                                                         L.sub.3      d.sub.3 =                                                                           0.360    1.651                                                                            55.9                                                r.sub.6 = -70.268                                                                           0.046 f.sub.min                                                         s.sub.3 =                                                                           0.584 f.sub.med                                                               0.907 f.sub.max                                                 r.sub.7 = ∞                                                        L.sub.4      d.sub.4 =                                                                           0.059    1.713                                                                            53.8                                                r.sub.8 = +0.836                                                                      s.sub.4 =                                                                           0.165                                                           r.sub.9 = -2.795                                                         L.sub.5      d.sub.5 =                                                                           0.056    1.643                                                                            58.0                                                r.sub.10 = +0.897                                                        L.sub.6      d.sub.6 =                                                                           0.149    1.847                                                                            23.8                                                r.sub.11 = +2.697                                                                           1.055 f.sub.min                                                         s.sub.5 =                                                                           0.748 f.sub.med                                                               0.194 f.sub.max                                                 r.sub.12 = +2.132                                                        L.sub.7      d.sub.7 =                                                                           0.137    1.620                                                                            60.3                                                r.sub.13 = ∞                                                                          0.578+0.155 f.sub.min                                                   s.sub.6 =                                                                           0.348+0.155 f.sub.med                                                         0.578+0.155 f.sub.max                                           r.sub.14 = +1.390            Φ.sub.14  = +0.4460                     L.sub.8      d.sub.8 =                                                                           0.186    1.620                                                                            60.3                                                r.sub.15 = -13.812                                                                    s.sub.7 =                                                                           0.006                                                           r.sub.16 = +0.923            Φ.sub.16 = +0.6717                      L.sub.9      d.sub.9 =                                                                           0.146    1.620                                                                            60.3                                                r.sub.17 = +2.200                                                                     s.sub.8 =                                                                           0.205                                                           r.sub.18 = -1.480            Φ.sub.18 = -0.5723                      L.sub.10     d.sub.10 =                                                                          0.233    1.847                                                                            23.8                                                r.sub.19 = +0.967            Φ.sub.19 = -0.8759                                   s.sub.9 =                                                                           0.168                                                           r.sub.20 = +5.158                                                        L.sub.11     d.sub.11 =                                                                          0.174    1.713                                                                            53.8                                                r.sub.21 = -0.923            Φ.sub.21 = +0.7725                                   s.sub.10  =                                                                         0.006                                                           r.sub.22 = +0.886            Φ.sub.22 = +0.7562                      L.sub.12     d.sub.12 =                                                                          0.124    1.670                                                                            47.1                                                r.sub.23 = +5.172                                                        __________________________________________________________________________     f.sub.min = 0.590                                                             f.sub.med = 1                                                                 f.sub.max = 1.637                                                             relative aperture = 1:1.2                                                     f.sub.2 = -0.807                                                              f.sub.3 = +3.438                                                         

                                      TABLE IV                                    __________________________________________________________________________                    Thicknesses and        Surface                                Lens Radii      Separations    n.sub.d                                                                           ν.sub.d                                                                        Powers                                 __________________________________________________________________________         r.sub.1                                                                          = +6.395                                                              L.sub.1         d.sub.1 =                                                                           0.106    1.805                                                                             25.4                                            r.sub.2                                                                          = +1.949                                                                              s.sub.1 =                                                                           0.143                                                        r.sub.3                                                                          = +2.542                                                              L.sub.2         d.sub.2 =                                                                           0.304    1.603                                                                             60.6                                            r.sub.4                                                                          = -13.652                                                                             s.sub.2 =                                                                           0.006                                                        r.sub.5                                                                          = +1.699                                                              L.sub.3         d.sub.3 =                                                                           0.360    1.651                                                                             55.9                                            r.sub.6                                                                          = -70.246                                                                                   0.043 f.sub.min                                                         s.sub.3 =                                                                           0.581 f.sub.med                                                               0.904 f.sub.max                                              r.sub.7                                                                          = -31.045                                                             L.sub.4         d.sub.4 =                                                                           0.059    1.713                                                                             53.8                                            r.sub.8                                                                          = +0.829                                                                              s.sub.4 =                                                                           0.165                                                        r.sub.9                                                                          = -3.415                                                              L.sub.5         d.sub.5 =                                                                           0.056    1.643                                                                             58.0                                            r.sub.10                                                                         = +0.897                                                              L.sub.6         d.sub.6 =                                                                           0.149    1.847                                                                             23.8                                            r.sub.11                                                                         = +2.395                                                                                    1.059 f.sub.min                                                         s.sub.5 =                                                                           0.752 f.sub.med                                                               0.198 f.sub.max                                              r.sub.12                                                                         = +2.132                                                              L.sub.7         d.sub.7 =                                                                           0.137    1.620                                                                             60.3                                            r.sub.13                                                                         =  ∞                                                                                  0.578+0.155 f.sub.min                                                   s.sub.6 =                                                                           0.348+0.155 f.sub.med                                                         0.578+0.155 f.sub.max                                        r.sub. 14                                                                        = +1.447                                                              L.sub.8         d.sub.8 =                                                                           0.186    1.620                                                                             60.3                                                                              Φ.sub.14 = +0.4285                      r.sub.15                                                                         = -5.554                                                                              s.sub.7 =                                                                           0.006                                                        r.sub.16                                                                         = +1.005                                                              L.sub.9         d.sub.9 =                                                                           0.146    1.620                                                                             60.3                                                                              Φ.sub.16 = +0.6169                      r.sub.17                                                                         = +2.528                                                                              s.sub.8 =                                                                           0.205                                                        r.sub.18                                                                         = -1.277                                                              L.sub.10        d.sub.10 =                                                                          0.233    1.847                                                                             23.8                                                                              Φ.sub.18 = -0.6633                      r.sub.19                                                                         = +0.987                                                                              s.sub.9 =                                                                           0.168            Φ.sub.19 = -0.8582                      r.sub.20                                                                         = +4.244                                                              L.sub.11        d.sub.11 =                                                                          0.174    1.713                                                                             53.8                                            r.sub.21                                                                         = -0.852                                                                              s.sub.10 =                                                                          0.006            Φ.sub.21 = +0.8369                      r.sub.22                                                                         = +0.830                                                              L.sub.12        d.sub.12 =                                                                          0.124    1.670                                                                             47.1                                                                              Φ.sub.22 = +0.8072                      r.sub.23                                                                         = +2.485                                                              __________________________________________________________________________     f.sub.min = 0.590                                                             f.sub.med = 1                                                                 f.sub.max = 1.638                                                             relative aperture = 1:1.2                                                     f.sub.2 = 0.807                                                               f.sub.3 = +3.438                                                         

                                      TABLE V                                     __________________________________________________________________________                 Thicknesses and      Surface                                     Lens Radii   Separations    n.sub.d                                                                          ν.sub.d                                                                       Powers                                      __________________________________________________________________________         r.sub.1 = +7.033                                                         L.sub.1      d.sub.1 =                                                                           0.114    1.805                                                                            25.4                                                r.sub.2 = +2.143                                                                      s.sub.1 =                                                                           0.158                                                           r.sub.3 = +2.796                                                         L.sub.2      d.sub.2 =                                                                           0.315    1.603                                                                            60.6                                                r.sub.4 = -15.015                                                                     s.sub.2 =                                                                           0.006                                                           r.sub.5 = +1.869                                                         L.sub.3      d.sub.3 =                                                                           0.360    1.651                                                                            55.9                                                r.sub.6 = -77.656                                                                           0.056 f.sub.min                                                         s.sub.3 =                                                                           0.660 f.sub.med                                                               1.018 f.sub.max                                                 r.sub.7 = ∞                                                        L.sub.4      d.sub.4 =                                                                           0.063    1.713                                                                            53.8                                                r.sub.8 = +0.905                                                                      s.sub.4 =                                                                           0.177                                                           r.sub.9 = -2.511                                                         L.sub.5      d.sub.5 =                                                                           0.063    1.643                                                                            58.0                                                r.sub.10 = +0.972                                                        L.sub.6      d.sub.6 =                                                                           0.164    1.847                                                                            23.8                                                r.sub.11 = +3.401                                                                           1.141 f.sub.min                                                         s.sub.5 =                                                                           0.828 f.sub.med                                                               0.269 f.sub.max                                                 r.sub.12 = +2.347                                                        L.sub.7      d.sub.7 =                                                                           0.139    1.620                                                                            60.3                                                r.sub.13 = ∞                                                                          0.644+0.158 f.sub.min                                                   s.sub.6 =                                                                           0.353+0.158 f.sub.med                                                         0.554+0.158 f.sub.max                                           r.sub.14 = +1.135            Φ.sub.14 =  +0.5463                     L.sub.8      d.sub.8 =                                                                           0.151    1.620                                                                            60.3                                                r.sub.15 = -4.127                                                                     s.sub.7 =                                                                           0.006                                                           r.sub.16 = +0.929            Φ.sub.16 = +0.6674                      L.sub.9      d.sub.9 =                                                                           0.148    1.620                                                                            60.3                                                r.sub.17 = +1.421                                                                     s.sub.8 =                                                                           0.208                                                           r.sub.18 = -1.024            Φ.sub.18 = -0.8271                      L.sub.10     d.sub.10 =                                                                          0.237    1.847                                                                            23.8                                                r.sub.19 = +0.948                                                                     s.sub.9 =                                                                           0.170                                                           r.sub.20 = +17.254           Φ.sub.19 = -0.8935                      L.sub.11     d.sub.11 =                                                                          0.170    1.713                                                                            53.8                                                r.sub.21 = -0.726            Φ.sub.21  = +0.9821                                  s.sub.10 =                                                                          0.006                                                           r.sub.22 = +0.831            Φ.sub.22 = +0.8063                      L.sub.12     d.sub.12 =                                                                          0.117    1.670                                                                            47.1                                                r.sub.23 = +2.965                                                        __________________________________________________________________________     f.sub.min = 0.589                                                             f.sub.med = 1                                                                 f.sub.max = 1.624                                                             relative aperture = 1:1.2                                                     f.sub.2 = -0.875                                                              f.sub.3 = +3.782                                                         

                                      TABLE VI                                    __________________________________________________________________________                 Thicknesses and      Surface                                     Lens Radii   Separations    n.sub.d                                                                          ν.sub.d                                                                       Powers                                      __________________________________________________________________________         r.sub.1 = +7.407                                                         L.sub.1      d.sub.1 =                                                                           0.106    1.805                                                                            25.4                                                r.sub.2 = +2.078                                                                      s.sub.1 =                                                                           0.143                                                           r.sub.3 = +2.777                                                         L.sub.2      d.sub.2 =                                                                           0.304    1.620                                                                            60.3                                                r.sub.4 = -14.400                                                                     s.sub.2 =                                                                           0.006                                                           r.sub.5 = +1.834                                                         L.sub.3      d.sub.3 =                                                                           0.373    1.720                                                                            50.4                                                r.sub.6 = -106.546                                                                          0.047 f.sub.min                                                         s.sub.3 =                                                                           0.585 f.sub.med                                                               0.908 f.sub.max                                                 r.sub.7 = -72.727                                                        L.sub.4      d.sub.4  =                                                                          0.059    1.713                                                                            53.8                                                r.sub.8 = +0.821                                                                      s.sub.4 =                                                                           0.165                                                           r.sub.9 = -2.394                                                         L.sub.5      d.sub.5 =                                                                           0.056    1.589                                                                            61.3                                                r.sub.10 = +0.913                                                        L.sub.6      d.sub.6 =                                                                           0.149    1.805                                                                            25.4                                                r.sub.11 = +2.835                                                                           1.030 f.sub.min                                                         s.sub.5 =                                                                           0.725 f.sub.med                                                               0.179 f.sub.max                                                 r.sub.12 = +2.090                                                        L.sub.7      d.sub.7 =                                                                           0.137    1.517                                                                            64.2                                                r.sub.13 = -11.604                                                                          0.581 + 0.280 f.sub.min                                                 s.sub.6 =                                                                           0.348 + 0.280 f.sub.med                                                       0.571 + 0.280 f.sub.max                                         r.sub.14 = +1.076            Φ.sub.14  = +0.5762                     L.sub.8      d.sub.8 =                                                                           0.196    1.620                                                                            60.3                                                r.sub.15 = ∞                                                                    s.sub.7 =                                                                           0.006                                                           r.sub.16 = +0.752            Φ.sub.16 = +0.8245                      L.sub.9      d.sub.9 =                                                                           0.149    1.620                                                                            60.3                                                r.sub.17 = +1.305                                                                     s.sub.9 =                                                                           0.155                                                           r.sub.18 = -1.886            Φ.sub.18 = -0.4491                      L.sub.10     d.sub.10 =                                                                          0.146    1.847                                                                            23.8                                                r.sub.19 = +0.802            Φ.sub.19 = -1.0562                                   s.sub.9 =                                                                           0.180                                                           r.sub.20 = ∞                                                       L.sub.11     d.sub.11 =                                                                          0.146    1.720                                                                            50.4                                                r.sub.21 = -0.974            Φ.sub.21 = +0.7392                                   s.sub.10 =                                                                          0.006                                                           r.sub.22 = +0.974            Φ.sub.22 = +0.7392                      L.sub.12     d.sub.12 =                                                                          0.146    1.720                                                                            50.4                                                r.sub.23 = ∞                                                       __________________________________________________________________________     f.sub.min = 0.591                                                             f.sub.med = 1                                                                 f.sub.max = 1.632                                                             relative aperture = 1:1.2                                                     f.sub.2 = -0.808                                                              f.sub.3 = +3.439                                                         

                                      TABLE VII                                   __________________________________________________________________________                Thicknesses and       Surface                                     Lens                                                                              Radii   Separations     n.sub.d                                                                          ν.sub.d                                                                       Powers                                      __________________________________________________________________________        r.sub.1 = +6.761                                                          L.sub.1     d.sub.1 =                                                                           0.106     1.805                                                                            25.4                                               r.sub.2 = +2.046                                                                      s.sub.1 =                                                                           0.155                                                           r.sub.3 = +2.744                                                          L.sub.2     d.sub.2 =                                                                           0.304     1.620                                                                            60.3                                               r.sub.4 = -17.711                                                                     s.sub.2 =                                                                           0.006                                                           r.sub.5 = +1.816                                                          L.sub.3     d.sub.3 =                                                                           0.373     1.720                                                                            50.4                                               r.sub.6 = -311.112                                                                          0.049 f.sub.min                                                         s.sub.3 =                                                                           0.588 f.sub.med                                                               0.910 f.sub.max                                                 r.sub.7 = -72.727                                                         L.sub.4     d.sub.4 =                                                                           0.059     1.713                                                                            53.8                                               r.sub.8 = +0.821                                                                      s.sub.4 =                                                                           0.165                                                           r.sub.9 = -2.394                                                          L.sub.5     d.sub.5 =                                                                           0.056     1.589                                                                            61.3                                               r.sub.10 = +0.913                                                         L.sub.6     d.sub.6 =                                                                           0.149     1.805                                                                            25.4                                               r.sub.11 = +2.835                                                                           1.030 f.sub.min                                                         s.sub.5 =                                                                           0.725 f.sub.med                                                               0.179 f.sub.max                                                 r.sub.12 = +2.090                                                         L.sub.7     d.sub.7 =                                                                           0.137     1.517                                                                            64.2                                               r.sub.13 = -11.604                                                                          0.581 + 0.280 f.sub.min                                                 s.sub.6 =                                                                           0.348 + 0.280 f.sub.med                                                       0.571 + 0.280 f.sub.max                                         r.sub.14 = +1.076             Φ.sub.14 = +0.5762                      L.sub.8     d.sub.8 =                                                                           0.196     1.620                                                                            60.3                                               r.sub.15 = ∞                                                                    s.sub.7 =                                                                           0.006                                                           r.sub.16 = +0.752             Φ.sub.16 = +0.8245                      L.sub.9     d.sub.9 =                                                                           0.149     1.620                                                                            60.3                                               r.sub.17 = +1.305                                                                     s.sub.8 =                                                                           0.155                                                           r.sub.18 = -1.886             Φ.sub.18 = -0.4491                      L.sub.10    d.sub.10 =                                                                          0.146     1.847                                                                            23.8                                               r.sub.19 = +0.802             Φ.sub.19 = -1.0562                                  s.sub.9 =                                                                           0.180                                                           r.sub.20 = ∞                                                        L.sub.11    d.sub.11 =                                                                          0.146     1.720                                                                            50.4                                               r.sub.21 = -0.974             Φ.sub.21 = +0.7392                                  s.sub.10 =                                                                          0.006                                                           r.sub.22 = +0.974             Φ.sub.22 = +0.7392                      L.sub.12    d.sub.12 =                                                                          0.146     1.720                                                                            50.4                                               r.sub.23 = ∞                                                        __________________________________________________________________________     f.sub.min = 0.591                                                             f.sub.med = 1                                                                 f.sub.max = 1.634                                                             relative aperture = 1:1.2                                                     f.sub.2 = -0.808                                                              f.sub.3 = +3.439                                                         

We claim:
 1. A pancratic objective comprising a varifocal front lensgroup and a fixed-focus rear lens group, said front lens groupconsisting of a substantially stationary first component of positiverefractivity, an axially shiftable second component of negativerefractivity and an axially shiftable third component of positiverefractivity, said third component being a weakly refractive single lenswhose individual focal length f₃ is related to the individual focallength f₂ of said second component by a ratio f₃ /|f₂ | exceeding 1.5times the ratio f_(max) /f_(min) where f_(max) is the maximum overallfocal length and f_(min) is the minimum overall focal length of saidvarifocal front lens group;said first component consisting of a negativefirst lens, a positive second lens and a positive third lens air-spacedfrom one another, said second component consisting of a negative fourthlens and a doublet composed of a negative fifth lens and a positivesixth lens, said third component constituting a seventh lens, said rearlens group consisting of five air-spaced lenses including a positiveeighth lens, a positive ninth lens, a negative tenth lens, a positiveeleventh lens and a positive twelfth lens, said eighth lens beinggenerally planocanvex and having a forwardly facing convex surface whosepower ranges between 0.4 and 0.7 times Φ_(med), said ninth lens being apositive meniscus having a forwardly facing convex surface whose powerranges between 0.6 and 0.9 times Φ_(med), said tenth lens beingbiconcave, said eleventh and twelfth lenses being generally planoconvex,Φ_(med) being the median power of the objective with said thirdcomponent in a position closest to said rear lens group.
 2. A pancraticobjective as defined in claim 1 wherein said tenth lens has a lessstrongly curved forwardly facing surface and a more stronly curvedrearwardly facing surface whose power ratio is less than 2.5, saideleventh lens having a rearwardly facing convex surface whose powerranges between 0.7Φ_(med) and Φ_(med), said twelfth lens having aforwardly facing convex surface whose power ranges between 0.7Φ_(med)and Φ_(med).
 3. A pancratic objective as defined in claim 1 or 2 wherein|f₂ |<f_(med).
 4. A pancratic objective as defined in claim 2 whereinsaid first lens L₁, said second lens L₂, said third lens L₃, said fourthlens L₄, said fifth lens L₅, said sixth lens L₆, said seventh lens L₇,said eighth lens L₈, said ninth lens L₉, said tenth lens L₁₀, saideleventh lens L₁₁ and said twelfth lens L₁₂ have radii r₁ to r₂₃,thicknesses d₁ to d₁₂ and separations s₁ to s₁₀ whose numerical values,based upon a value of unity for a median overall focal length f_(med),together with their refractive indices n_(d) and Abbe numbers ν_(d) aresubstantially as given in the following table:

    ______________________________________                                                         Thicknesses and                                              Lens   Radii     Separations      n.sub.d                                                                             ν.sub.d                            ______________________________________                                                   r.sub.1 = +6.4                                                     L.sub.1              d.sub.1 = 0.11       1.8   25                                       r.sub.2 = +2.0                                                                          s.sub.1 = 0.14                                                      r.sub.3 = +2.7                                                     L.sub.2              d.sub.2 = 0.31       1.60  61                                       r.sub.4 = -13.8                                                                         s.sub.2 = 0.01                                                      r.sub.5 = +1.7                                                     L.sub.3              d.sub.3 = 0.37       1.66  51                                       r.sub.6 = -42.5                                                                                   0.05 f.sub.min                                                      s.sub.3 = 0.59 f.sub.med                                                                0.91 f.sub.max                                            r.sub.7 = -72.8                                                    L.sub.4                                                                                            d.sub.4 = 0.06       1.71  54                                       r.sub.8 = +0.8                                                                          s.sub.4 = 0.17                                                      r.sub.9 = -2.4                                                     L.sub.5              d.sub.5 = 0.06       1.59  61                                       r.sub.10 = +0.9                                                    L.sub.6              d.sub.6 = 0.15       1.81  25                                       r.sub.11 = +2.8                                                                                   1.03 f.sub.min                                                      s.sub.5 = 0.73 f.sub.med                                                                0.18 f.sub.max                                            r.sub.12 = +2.1                                                    L.sub.7              d.sub.7 = 0.14       1.52  64                                       r.sub.13 = -11.6                                                                                  0.58 +0.28 f.sub.min                                                s.sub.6 = 0.35 +0.28 f.sub.med                                                          0.57 +0.28 f.sub.max                                      r.sub.14 = +1.0                                                    L.sub.8                                                                                            d.sub.8 = 0.21       1.62  60                                       r.sub.15 = -10.4                                                                        s.sub.7 = 0.01                                                      r.sub.16 = +0.8                                                    L.sub.9              d.sub.9 = 0.14       1.62  47                                       r.sub.17 = +1.7                                                                         s.sub.8 = 0.14                                                      r.sub.18 = -1.5                                                    L.sub.10             d.sub.10 =                                                                              0.14       1.85  24                                       r.sub.19 = +0.8                                                                         s.sub.9 = 0.21                                                      r.sub.20 = -56.8                                                   L.sub.11             d.sub.11 =                                                                              0.17       1.71  54                                       r.sub.21 = -0.8                                                                         s.sub.10 =                                                                              0.01                                                      r.sub.22 = +0.9                                                    L.sub.12             d.sub.12 =                                                                              0.12       1.72  48                                       r.sub.23 = +2.4                                                    ______________________________________                                    


5. A pancratic objective as defined in claim 2 wherein said first lensL₁, said second lens L₂, said third lens L₃, said fourth lens L₄, saidfifth lens L₅, said sixth lens L₆, said seventh lens L₇, said eighthlens L₈, said ninth lens L₉, said tenth lens L₁₀, said eleventh lens L₁₁and said twelfth lens L₁₂ have radii r₁ to r₂₃, thicknesses d₁ to d₁₂and separations s₁ to s₁₀ whose numerical values, based upon a value ofunity for a median overall focal length f_(med), together with theirrefractive indices n_(d) and Abbe numbers ν_(d) are substantially asgiven in the following table:

    ______________________________________                                                           Thicknesses and                                            Lens   Radii       Separations      n.sub.d                                                                            ν.sub.d                           ______________________________________                                                   r.sub.1 = +6.4                                                     L.sub.1                d.sub.1 = 0.11       1.81 25                                      r.sub.2 = +2.0                                                                            s.sub.1 = 0.14                                                    r.sub.3 = +2.6                                                     L.sub.2                d.sub.2 = 0.30       1.60 61                                      r.sub.4 = -13.7                                                                           s.sub.2 = 0.01                                                    r.sub.5 = +1.7                                                     L.sub.3                d.sub.3 = 0.36       1.65 56                                      r.sub.6 = -70.3                                                                                     0.05  f.sub.min                                                     s.sub.3 = 0.58  f.sub.med                                                               0.91  f.sub.max                                         r.sub.7 = ∞                                                  L.sub.4                d.sub.4 = 0.06       1.71 54                                      r.sub.8 = +0.8                                                                            s.sub.4 = 0.17                                                    r.sub.9 = -2.8                                                     L.sub.5                d.sub.5 = 0.06       1.64 58                                      r.sub.10 = +0.9                                                    L.sub.6                d.sub.6 = 0.15       1.85 24                                      r.sub.11 = +2.7                                                                                     1.06  f.sub.min                                                     s.sub.5 = 0.75  f.sub.med                                                               0.19  f.sub.max                                         r.sub.12 = +2.4                                                    L.sub.7                d.sub.7 = 0.14       1.70 55                                      r.sub.13 = ∞                                                                                  0.58  +0.16                                                                              f.sub.min                                                s.sub.6 = 0.35  +0.16                                                                              f.sub.med                                                          0.58  +0.16                                                                              f.sub.max                                    r.sub.14 = +1.5                                                    L.sub.8                d.sub.8 = 0.19       1.62 60                                      r.sub.15 = -6.7                                                                           s.sub.7 = 0.01                                                    r.sub.16 = +0.9                                                    L.sub.9                d.sub.9 = 0.15       1.62 60                                      r.sub.17 = +2.1                                                                           s.sub.8 = 0.21                                                    r.sub.18 = -1.7                                                    L.sub.10               d.sub.10 =                                                                              0.14       1.85 24                                      r.sub.19 = +0.9                                                                           s.sub.9 = 0.26                                                    r.sub.20 = +9.2                                                    L.sub.11               d.sub.11 =                                                                              0.17       1.71 54                                      r.sub.21 = +1.0                                                                           s.sub.10 =                                                                              0.01                                                    r.sub.22 = +0.9                                                    L.sub.12               d.sub.12 =                                                                              0.12       1.72 48                                      r.sub.23 = +4.5                                                    ______________________________________                                    


6. A pancratic objective as defined in claim 1 wherein said first lensL₁, said second lens L₂, said third lens L₃, said fourth lens L₄, saidfifth lens L₅, said sixth lens L₆, said seventh lens L₇, said eighthlens L₈, said ninth lens L₉, said tenth lens L₁₀, said eleventh lens L₁₁and said twelfth lens L₁₂ have radii r₁ to r₂₃, thicknesses d₁ to d₁₂and separations s₁ to s₁₀ whose numerical values, based upon a value ofunity for a median overall focal length f_(med), together with theirrefractive indices n_(d) and Abbe numbers ν_(d) are substantially asgiven in the following table:

    ______________________________________                                                          Thicknesses and                                             Lens   Radii      Separations       n.sub.d                                                                            ν.sub.4                           ______________________________________                                                   r.sub.1 = +6.4                                                     L.sub.1               d.sub.1 = 0.11      1.81 25                                        r.sub.2 = +2.0                                                                           s.sub.1 = 0.14                                                     r.sub.3 = +2.6                                                     L.sub.2               d.sub.2 = 0.30      1.60 61                                        r.sub.4 = -13.7                                                                          s.sub.2 = 0.01                                                     r.sub.5 = +1.7                                                     L.sub.3               d.sub.3 = 0.36      1.65 56                                        r.sub.6 = -70.3                                                                                    0.05 f.sub.min                                                      s.sub.3 = 0.58 f.sub.med                                                                0.91 f.sub.max                                           r.sub.7 =  ∞                                                 L.sub.4               d.sub.4  =                                                                              0.06      1.71 54                                        r.sub.8 = +0.8                                                                           s.sub.4 = 0.17                                                     r.sub.9 = -2.8                                                     L.sub.5               d.sub.5 = 0.06      1.64 58                                        r.sub.10 = +0.9                                                    L.sub.6               d.sub.6 = 0.15      1.85 24                                        r.sub.11 = +2.7                                                                                    1.06 f.sub.min                                                      s.sub.5 = 0.75 f.sub.med                                                                0.19 f.sub.max                                           r.sub.12 = +2.1                                                    L.sub.7               d.sub.7 = 0.14      1.62 60                                        r.sub.13 =   ∞                                                                               0.58 + 0.16 f.sub.min                                               s.sub.6 = 0.35 + 0.16 f.sub.med                                                         0.58 + 0.16 f.sub.max                                    r.sub.14 = +1.4                                                    L.sub.8               d.sub.8  =                                                                              0.19      1.62 60                                        r.sub.15 = -13.8                                                                         s.sub.7 = 0.01                                                     r.sub.16 = +0.9                                                    L.sub.9               d.sub.9 = 0.15      1.62 60                                        r.sub.17 = +2.2                                                                          s.sub.8 = 0.21                                                     r.sub.18 = -1.5                                                    L.sub.10              d.sub.10 =                                                                              0.23      1.85 24                                        r.sub.19 = +1.0                                                                          s.sub.9 = 0.17                                                     r.sub.20 = +5.2                                                    L.sub.11              d.sub.11 =                                                                              0.17      1.71 54                                        r.sub.21 = -0.9                                                                          s.sub.10 =                                                                              0.01                                                     r.sub.22 = +0.9                                                    L.sub.12              d.sub.12 =                                                                              0.12      1.67 47                                        r.sub.23 = +5.2                                                    ______________________________________                                    


7. A pancratic objective as defined in claim 1 wherein said first lensL₁, said second lens L₂, said third lens L₃, said fourth lens L₄, saidfirth lens L₅, said sixth lens L₆, said seventh lens L₇, said eighthlens L₈, said ninth lens L₉, said tenth lens L₁₀, said eleventh lens L₁₁and said twelfth lens L₁₂ have radii r₁ to r₂₃, thicknesses d₁ to d₁₂and separations s₁ to s₁₀ whose numerical values, based upon a value ofunity for a median overall focal length f_(med), together with theirrefractive indices n_(d) and Abbe numbers ν_(d) are substantially asgiven in the following table:

    ______________________________________                                                               Thicknesses and                                        Lens   Radii           Separations  n.sub.d                                                                            ν.sub.d                           ______________________________________                                                   r.sub.1 = +6.4                                                     L.sub.1              d.sub.1 = 0.11       1.81 25                                        r.sub.2 = +1.9                                                                          s.sub.1 = 0.14                                                      r.sub.3 = +2.5                                                     L.sub.2              d.sub.2 = 0.30       1.60 61                                        r.sub.4 = -13.7                                                                         s.sub.2 = 0.01                                                      r.sub.5 = +1.7                                                     L.sub.3              d.sub.3 = 0.36       1.65 56                                        r.sub.6 = -70.3                                                                                   0.04 f.sub.min                                                      s.sub.3 = 0.58 f.sub.med                                                                0.90 f.sub.max                                            r.sub.7 = -31.0                                                    L.sub.4                                                                                            d.sub.4 = 0.06       1.71 54                                        r.sub.8 = +0.8                                                                          s.sub.4 = 0.17                                                      r.sub.9 = -3.4                                                     L.sub.5              d.sub.5 = 0.06       1.64 58                                        r.sub.10 = +0.9                                                    L.sub.6              d.sub.6 = 0.15       1.85 24                                        r.sub.11 = +2.4                                                                                   1.06 f.sub.min                                                      s.sub.5 = 0.75 f.sub.med                                                                0.20 f.sub.max                                            r.sub.12 = +2.1                                                    L.sub.7              d.sub.7 = 0.14       1.62 60                                        r.sub.13 = ∞  0.58 +  0.16 f.sub.min                                              s.sub.6 = 0.35 + 0.16 f.sub.med                                                         0.58 +  0.16 f.sub.max                                    r.sub.14 = +1.4                                                    L.sub.8              d.sub. 8 =                                                                              0.19       1.62 60                                        r.sub.15 = -5.6                                                                         s.sub.7 = 0.01                                                      r.sub.16 = +1.0                                                    L.sub.9              d.sub.9 = 0.15       1.62 60                                        r.sub.17 = +2.5                                                                         s.sub.8 = 0.21                                                      r.sub.18 = -1.3                                                    L.sub.10             d.sub.10 =                                                                              0.23       1.85 24                                        r.sub.19 = +1.0                                                                         s.sub.9 = 0.17                                                      r.sub.20 = +4.2                                                    L.sub.11             d.sub.11 =                                                                              0.17       1.71 54                                        r.sub.21 = -0.9                                                                         s.sub.10 =                                                                              0.01                                                      r.sub.22 = +.08                                                    L.sub.12             d.sub.12 =                                                                              0.12       1.67 47                                        r.sub.23 = +2.5                                                    ______________________________________                                    


8. A pancratic objective as defined in claim 2 wherein said first lensL₁, said second lens L₂, said third lens L₃, said fourth lens L₄, saidfifth lens L₅, said sixth lens L₆, said seventh lens L₇, said eighthlens L₈, said ninth lens L₉, said tenth lens L₁₀, said eleventh lens L₁₁and said twelfth lens L₁₂ have radii r₁ to r₂₃, thicknesses d₁ to d₁₂and separations s₁ to s₁₀ whose numerical values, based upon a value ofunity for a median overall focal length f_(med), together with theirrefractive indices n_(d) and Abbe numbers ν_(d) are substantially asgiven in the following table:

    ______________________________________                                                          Thicknesses and                                             Lens   Radii      Separations       n.sub.d                                                                            ν.sub.d                           ______________________________________                                                   r.sub.1 = +7.0                                                     L.sub.1               d.sub.1 = 0.11      1.81 25                                        r.sub.2 = +2.1                                                                           s.sub.1 = 0.16                                                     r.sub.3 = +2.8                                                     L.sub.2               d.sub.2 = 0.32      1.60 61                                        r.sub.4 = -15.0                                                                          s.sub.2 = 0.01                                                     r.sub.5 = +1.9                                                     L.sub.3               d.sub.3 = 0.36      1.65 56                                        r.sub.6 = -77.7                                                                                    0.06 f.sub.min                                                      s.sub.3 = 0.66 f.sub.med                                                                1.02 f.sub.max                                           r.sub.7 =  ∞                                                 L.sub.4               d.sub.4 = 0.06      1.71 54                                        r.sub.8 = +0.9                                                                           s.sub.4 = 0.18                                                     r.sub.9 = -2.5                                                     L.sub.5               d.sub.5 = 0.06      1.64 58                                        r.sub.10 = +1.0                                                    L.sub.6               d.sub.6 = 0.16      1.85 24                                        r.sub.11 = +3.4                                                                                    1.14 f.sub.min                                                      s.sub.5 = 0.83 f.sub.med                                                                0.27 f.sub.max                                           r.sub.12 = +2.3                                                    L.sub.7               d.sub.7 = 0.14      1.62 60                                        r.sub.13 =  ∞                                                                                0.64 + 0.16 f.sub.min                                               s.sub.6 = 0.35 + 0.16 f.sub.med                                                         0.55 + 0.16 f.sub.max                                    r.sub.14 = +1.1                                                    L.sub.8               d.sub. 8 =                                                                              0.15      1.62 60                                        r.sub.15 = -4.1                                                                          s.sub.7 = 0.01                                                     r.sub.16 = +0.9                                                    L.sub.9               d.sub.9 = 0.15      1.62 60                                        r.sub.17 = +1.4                                                                          s.sub.8 = 0.21                                                     r.sub.18 = -1.0                                                    L.sub.10              d.sub.10 =                                                                              0.24      1.85 24                                        r.sub.19 = +0.9                                                                          s.sub.9 = 0.17                                                     r.sub.20 = +17.3                                                   L.sub.11              d.sub.11 =                                                                              0.17      1.71 54                                        r.sub.21 = -0.7                                                                          s.sub.10 =                                                                              0.01                                                     r.sub.22 = +0.8                                                    L.sub.12              d.sub.12 =                                                                              0.12      1.67 47                                        r.sub.23 = +3.0                                                    ______________________________________                                    


9. A pancratic objective as defined in claim 2 wherein said first lensL₁, said second lens L₂, said third lens L₃, said fourth lens L₄, saidfifth lens L₅, said sixth lens L₆, said seventh lens L₇, said eighthlens L₈, said ninth lens L₉, said tenth lens L₁₀, said eleventh lens L₁₁and said twelfth lens L₁₂ have radii r₁ to r₂₃, thicknesses d₁ to d₁₂and separations s₁ to s₁₀ whose numerical values, based upon a value ofunity for a median overall focal length f_(med), together with theirrefractive indices n_(d) and Abbe numbers ν_(d) are substantially asgiven in the following table:

    ______________________________________                                                          Thicknesses and                                             Lens   Radii      Separations       n.sub.d                                                                            ν.sub.d                           ______________________________________                                                   r.sub.1 = +7.4                                                     L.sub.1               d.sub.1 = 0.11      1.81 25                                        r.sub.2 = +2.1                                                                           s.sub.1 = 0.14                                                     r.sub.3 = +2.8                                                     L.sub.2               d.sub.2 = 0.30      1.62 60                                        r.sub.4 = -14.4                                                                          s.sub.2 = 0.01                                                     r.sub.5 = +1.8                                                     L.sub.3               d.sub.3 = 0.37      1.72 50                                        r.sub.6 = -106.5                                                                                   0.05 f.sub.min                                                      s.sub.3 = 0.59 f.sub.med                                                                0.91 f.sub.max                                           r.sub.7 = -72.7                                                    L.sub.4               d.sub. 4 =                                                                              0.06      1.71 54                                        r.sub.8 = +0.8                                                                           s.sub.4 = 0.17                                                     r.sub.9 = -2.4                                                     L.sub.5               d.sub.5 = 0.06      1.59 61                                        r.sub.10 = +0.9                                                    L.sub.6               d.sub.6 = 0.15      1.81 25                                        r.sub.11 = +2.8                                                                                    1.03 f.sub.min                                                      s.sub.5 = 0.73 f.sub.med                                                                0.18 f.sub.max                                           r.sub.12 = +2.1                                                    L.sub.7               d.sub.7 = 0.14      1.52 64                                        r.sub.13 = -11.6                                                                                   0.58 + 0.28 f.sub.min                                               s.sub.6 = 0.35 + 0.28 f.sub.med                                                         0.57 + 0.28 f.sub.max                                    r.sub.14 = +1.1                                                    L.sub.8               d.sub.8  =                                                                              0.20      1.62 60                                        r.sub.15 = ∞                                                                       s.sub.7 = 0.01                                                     r.sub.16 = +0.8                                                    L.sub.9               d.sub.9 = 0.15      1.62 60                                        r.sub.17 = +1.3                                                                          s.sub.8 = 0.16                                                     r.sub.18 = -1.9                                                    L.sub.10              d.sub.10 =                                                                              0.15      1.85 24                                        r.sub.19 = +0.8                                                                          s.sub.9 = 0.18                                                     r.sub.20 = ∞                                                 L.sub.11              d.sub.11 =                                                                              0.15      1.72 50                                        r.sub.21 = -1.0                                                                          s.sub.10 =                                                                              0.01                                                     r.sub.22 = +1.0                                                    L.sub.12              d.sub.12 =                                                                              0.15      1.72 50                                        r.sub.23 = ∞                                                 ______________________________________                                    


10. A pancratic objective as defined in claim 2 wherein said first lensL₁, said second lens L₂, said third lens L₃, said fourth lens L₄, saidfifth lens L₅, said sixth lens L₆, said seventh lens L₇, said eighthlens L₈, said ninth lens L₉, said tenth lens L₁₀, said eleventh lens L₁₁and said twelfth lens L₁₂ have radii r₁ to r₂₃, thicknesses d₁ to d₁₂and separations s₁ to s₁₀ whose numerical values, based upon a value ofunity for a median overall focal length f_(med), together with theirrefractive indices n_(d) and Abbe numbers ν_(d) are substantially asgiven in the following table:

    __________________________________________________________________________                    Thicknesses and                                               Lens Radii      Separations    n.sub.d                                                                          ν.sub.d                                  __________________________________________________________________________         r.sub.1 = +6.8                                                           L.sub.1         d.sub.1 =                                                                           0.11     1.81                                                                             25                                               r.sub.2 = +2.0                                                                           s.sub.1 =                                                                           0.16                                                         r.sub.3 = +2.7                                                           L.sub.2         d.sub.2 =                                                                           0.30     1.62                                                                             60                                               r.sub.4 = -17.7                                                                          s.sub.2 =                                                                           0.01                                                         r.sub.5 = +1.8                                                           L.sub.3         d.sub.3 =                                                                           0.37     1.72                                                                             50                                               r.sub.6 = -311.1                                                                               0.05 f.sub.min                                                          s.sub.3 =                                                                           0.59 f.sub.med                                                                0.91 f.sub.max                                               r.sub.7 = -72.7                                                          L.sub.4                                                                                       d.sub.4 =                                                                           0.06     1.71                                                                             54                                               r.sub.8 = +0.8                                                                           s.sub.4 =                                                                           0.17                                                         r.sub.9 = -2.4                                                           L.sub.5         d.sub.5 =                                                                           0.06     1.59                                                                             61                                               r.sub.10 = +0.9                                                          L.sub.6         d.sub.6 =                                                                           0.15     1.81                                                                             25                                               r.sub.11 = +2.8                                                                                1.03 f.sub.min                                                          s.sub.5 =                                                                           0.73 f.sub.med                                                                0.18 f.sub.max                                               r.sub.12 = +2.1                                                          L.sub.7         d.sub.7 =                                                                           0.14     1.52                                                                             64                                               r.sub.13 = -11.6                                                                               0.58 + 0.28 f.sub.min                                                   s.sub.6 =                                                                           0.35 + 0.28 f.sub.med                                                         0.57 + 0.28 f.sub.max                                        r.sub.14 = +1.08                                                         L.sub.8                                                                                       d.sub.8 =                                                                           0.20     1.62                                                                             60                                               r.sub.15 =   ∞                                                                     s.sub.7 =                                                                           0.01                                                         r.sub.16 = +0.8                                                          L.sub.9         d.sub.9 =                                                                           0.15     1.62                                                                             60                                               r.sub.17 = +1.3                                                                          s.sub.8 =                                                                           0.16                                                         r.sub.18 = -1.9                                                          L.sub.10        d.sub.10 =                                                                          0.15     1.85                                                                             24                                               r.sub.19 = +0.8                                                                          s.sub.9 =                                                                           0.18                                                         r.sub.20 =  ∞                                                      L.sub.11        d.sub.11 =                                                                          0.15     1.72                                                                             50                                               r.sub.21 = -1.0                                                                          s.sub.10 =                                                                          0.01                                                         r.sub.22 = +1.0                                                          L.sub.12        d.sub.12 =                                                                          0.15     1.72                                                                             50                                               r.sub.23 =   ∞                                                     __________________________________________________________________________